Geography Reference
In-Depth Information
4 Related Work
4.1 Augmented Reality
Research on Augmented Reality (AR) in general has started as early as display
technology reached sufficiently high levels of complexity to allow dynamic
overlays of video streams. We refer the reader to a number of AR survey articles,
such as Azuma (
1995
). However, the work on mobile augmented reality has been
prohibited by a number of factors, most of which were related to the complexity
and size of the hardware that needed to be carried around. One of the earliest
systems was a Touring machine, a mobile AR system for exploring the urban
environment (Feiner et al.
1997
). Since the late 1990s a number of prototypes have
been developed, among others the ARToolkit system (Piekarski and Thomas
2002
). Two of the more recent widely known mobile AR systems are Layar and
Wikitude. Layar (Layar
2011
) is a mobile application that augments the real view
with a number of overlay layers (free and paid). Wikitude is a bundle of AR
software for mobile phones. It includes two different projects, the Wikitude Drive
and Wikitude Browser (Karpischek et al.
2009
). The content was primarily
extracted from the existing web sites, such as Wikipedia.
For social reality annotations there have been a number of research initiatives,
such as interactive virtual graffiti (Lim and Aylett
2004
; Coulton et al.
2006
).
Many of these systems share similar overall design and features, but differ in the
feature set, underlying technology or actual purpose.
For more detailed analysis of mobile augmented reality we recommend survey
articles, for example (Papagiannakis et al.
2008
).
4.2 Mobile Annotation Systems
There are many systems that allow location tagging, and many mainstream sys-
tems provide the ability to attach location information to their content (e.g. Twitter
added this functionality relatively early on). Nevertheless, spatiotemporal anno-
tation systems are relatively uncharted territory. It is widely acknowledged that the
area of user-generated content that is time- and location-dependent has potential,
especially in the context of geographical information systems, yet there are no
standard ways to manage, display and manipulate such content.
An early example of an annotation system that puts space and time to use is
''GeoNote'' (Persson et al.
2002
). This system was tested by students using lap-
tops in several specific LAN hotspots. These wireless LAN hotspots were used to
identify the area of the current users.
Other more recent systems make use of mobile phones with built in GPS units,
which send SMS messages with the location of the mobile device and create a
virtual
''post
it''
with
this
information
(Siemens
2005
).
Another
system
